Conventionally, various lighting devices have been proposed for various purposes. As the light source in lighting devices, while fluorescent lamps are common, in recent years, LEDs are also increasingly used. Also as to the control of lighting devices, various proposals have been made. For example, according to one proposal, in a lighting system, based on various kinds of detected information on the ambient environment of lighting appliances, a plurality of lighting appliances are controlled to achieve lighting control more suitable to the ambient environment of the lighting appliances; moreover, increased flexibility in system design is achieved (Patent Document 1). According to another proposal, control based on a human detection sensor is achieved (Patent Document 2).